The invention relates to a bearing for high rotational speeds, consisting of a stationary and a rotatable race ring in between rolling elements placed in a cage, and a lubricating means for supplying lubricant to the races of the bearing.
In known high speed running bearing assemblies the lubricating means is provided with a pump to secure a desired pressure of the lubricant. Besides, this necessitates a comparatively complicated circulating, filtering and pressure regulating system, whereby the construction of the bearing is rendered additionally costly and difficult.
The object of the invention is to provide a bearing of the kind mentioned in the preamble, in which the stated disadvantages are avoided and which moreover is simple in design and effective in operation.
According to the invention, the bearing is characterized in that at least on one side of said stationary race, a ring made of porous material is fixed, adjoined by a source of lubricant an end part thereof extending into the vicinity of the running surface of the rotating race, such that the lubricant, under the influence of the negative pressure generated by high rotation being drawn out from said end part and moved from the said part, mainly in radial direction to the said stationary race ring and returned to the porous ring once more along the running surface of said stationary race ring.
The negative pressure at the rotating race is induced by the centrifugal force generated in rotation, whereby the lubricant is drawn out of the porous ring to the races to be lubricated; a lubricant pump with regulating systems is thus superfluous. Because the running surface of the stationary race returns the lubricant to the porous ring, a circulation of lubricant is set up through the porous ring and the bearing, whereby the lubricant is continually replenished on the parts to be lubricated, and the service life of the bearing is considerably prolonged. A contributory effect to this is that dirt particles are retained in the porous ring and thus removed from the lubricant, so that the bearing is actually lubricated at all times by lubricant of optimum quality.
It is noted that Netherlands Patent Application 7,304,414 discloses a bearing for low speeds, provided with a lubricating means in which no pump is used likewise. Here use is made of a grease compound from which the lubricant is released in rotation by centrifugal force. The rotational speed, however, is comparatively low, in this case about 660 revolutions per minutes, inasmuch as the grease compound is unable to flow. The invention, by contrast, relates to a bearing for very high rotational speeds, for example over 15,000 revolutions per minute, so that the prior art lubricating system suitable for low rotational speeds cannot be employed.
Preferably, according to the invention, a porous ring or plate is fixed on opposed sides of the stationary race provided with an end part which is close to said rolling elements and rotatable race ring, at least has no contact with these bearing parts.
An especially simple design is achieved when the source of lubricant consists of an absorbent ring or similar member saturated with lubricant and arranged in a recess formed in the (each) porous ring and adjoining the stationary race.
According to an advantageous embodiment of the invention, a sealing ring is arranged on the inner side of the (each) porous ring, extending into the vicinity of the stationary race, thus achieving a favorable circulation of the lubricant.